COLOGNE, Germany -- Manchester United manager Ole Gunnar Solskjaer says he will not be able to keep three top-level goalkeepers happy next season as he prepares to welcome back Dean Henderson from a successful loan spell at Sheffield United.

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Henderson, 23, has forced himself into England reckoning with his performances at Bramall Lane and will return to Old Trafford as one of the most highly-rated young goalkeepers in the world.

Solskjaer already has Spain No.1 David de Gea and Argentina keeper Sergio Romero in his squad and the Norwegian has hinted that one of them will have to leave this summer.

"Competition for places is important and we're looking to have competition for places," said Solskjaer. "We have Dean, Sergio and David in the ranks but it'll be difficult obviously to keep three of them at the club. We'll see what the decision will be there."

Henderson is on holiday after helping Sheffield United to a ninth-place finish in the Premier League leaving Solskjaer to choose between De Gea and Romero when the Europa League mini-tournament kicks off in Cologne against FC Copenhagen on Monday night.

Romero has played in eight Europa League ties this season but Solskjaer is not ruling out drafting in De Gea, as he did for the FA Cup semifinal defeat to Chelsea when the Spaniard made two crucial errors in the 3-1 defeat at Wembley.

"I must be the most privileged manager in the world with the goalkeeping department -- Sergio, David and Dean coming back," said Solskjaer. "They are three top [keepers] and this Europa League has shown how important Sergio has been for us and David has always been performing. We'll see what we'll do going forward."